1. Field of the Invention
The present invention relates to a process for forming a multilayer film comprising a solid-color coating film and a clear coating film. More particularly, the present invention relates to a process for forming a multilayer film having reduced thickness and improved properties such as hiding power, surface smoothness, chipping resistance and the like.
2. Description of the Prior Art
Previous processes for forming a multilayer film include applying a solid-color coating and a clear coating onto a substrate on a wet-on-wet basis, and heat-curing the films. Various coloring agents can be used in such previously known processes, including inorganic and organic coloring pigments such as titanium dioxide, zinc white, carbon black, Cadmium Red, Molybdenum Red, Chrome Yellow, chrome oxide, Prussian Blue, Cobalt Blue, Azo pigments, Phthalocyanine pigments, Quinacridone pigments, Isoindoline pigments, threne derivative pigments, perylene derivative pigments and the like.
The multilayer film formed by the above approach can lack sufficient hiding power for solid-color film depending on the kind of pigment used (which can necessitate the formation of a thick solid-color film, for example, 25 micrometers or more) and which can be inferior in color stability. These drawbacks of the multilayer film can be very serious when the multilayer film is formed on the body panel of an automobile wherein the appearance of the film is important.